In semiconductor manufacturing facilities, teaching reproduction type robots are frequently used for transport of a semiconductor wafer between a container and a processing apparatus or between processing apparatus. Work of teaching such a robot is such that an operator manually teaches a robot the position of a semiconductor wafer by manipulating a teaching pendant while looking at the semiconductor wafer that is placed inside a container or the like.
Other methods are also available, examples of which are a method of directly inputting the position of a semiconductor wafer on the basis of a system drawing of semiconductor manufacturing facilities (i.e., a drawing indicating positional relationships between robots, containers, etc.) and what is called off-line teaching in which the position of a semiconductor wafer is taught while a simulation is performed on a personal computer. However, even with those methods, it is necessary to directly teach a robot manually for each apparatus to correct for calibration errors of the robot itself, errors resulting from the accuracy of finishing of each apparatus, attachment errors, etc.
Various kinds of what is called auto-teaching have been proposed in which a distance sensor is attached to the hand of a robot and the robot is positioned automatically by detecting a subject being transported with the distance sensor (e.g., Japanese Patent No. 2,898,587 and JP-A-10-6262).
However, in conventional methods, in many cases it is difficult for an operator to approach a container or a processing device. It may be difficult or impossible for an operator to directly see a semiconductor wafer, in which case trial-and-error attempts need to be made repeatedly.
Since the quality of teaching work depends on the individual operator, there is a problem that variation occurs in the operation of a robot even in the same system.
In conventional auto-teaching methods, the position of a wafer is estimated on the basis of information detected by a distance sensor that operates in one direction. This results in a problem that the accuracy of the direction of a wafer is not satisfactory though the distance between a wafer and a robot can be determined with relatively high accuracy.
Conventional teaching jigs are composed of a large disc portion and a small disc portion and hence are thick, which leads to a problem that the installation space is restricted in height.